Materials in granular and powder form are typically stored and transported in large containers, commonly referred to in the industry as bulk bags or fiber intermediate bulk containers (F.I.B.C.). These bulk bags are usually made of woven fabrics such as woven polypropylene which are capable of holding large, heavy quantities of materials, typically weighing a ton or so. Liners are commonly used for the interior of bulk bags to provide a moisture barrier or to render the bag capable of containing liquids. Conventional liners are made of flexible materials such as polyethylene or nylon that are either tubular, i.e. tube liners, or specifically configured to conform to the shape of the bulk bag, i.e. form-fitted liners. Exemplary of such lined bulk bags is that shown in U.S. Pat. No. 5,762,421.
In order to unload a lined bulk bag, both the bulk bag and its liner are commonly provided with discharge chutes or spouts that depend from their bottoms. Form fitted liners have distinct spouts that extend from the liner bottom. The discharge spouts of tube liners however are indistinct, they merely being a bottom portion of the tube that has been contracted to fit through the discharge spout of the bulk bag.
Prior to being unloaded the liner discharge spout has been tied off with a tie cord and tucked away to one side of the bag spout between the bottom of the liner and bottom of the bag. The bag spout is usually also tied off. To unload the bag it is suspended as by four corner loops over a hopper. The bag spout is then untied and unfurled into its tubular shape. A worker then reaches up through the bag spout and feels for the tied off liner spout. Manually locating and grabbing it below the tie off is not an easy task since the exposed bottom area of the liner is wrinkled. This wrinkling is extensive where the liner is a tube type liner since its spout has been formed by contracting and wrinkling a bottom portion of itself. Once located it still is difficult to dislodge the liner spout from its position sandwiched between the bottom of the liner and bag due to the weight of the load. Note that a fully loaded bulk bag can easily weight several thousand pounds. Once the liner spout is located and pulled down into the bag spout, its tie off becomes manually accessible. After the spouts have been placed over the hopper, the liner tie off is released whereupon material flows down through the bag and liner spouts and into the hopper.
It thus is seen that the unloading of lined bulk bags has been a challenging task with risks of both personal injury and of accidental discharge. Were a liner bulk bag to be devised that would facilitate unloading and reduce these risks, a distinct advantage would be achieved.
Accordingly, it is to the provision of such that this invention is primarily directed.